Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$209.29	3.146%	$215.8743	$215.87	$215.85	$215.90
Purchase #2	$200.29	7.816%	$215.9447	$215.94	$215.95	$215.90
Purchase #3	$20.72	4.398%	$21.6313	$21.63	$21.65	$21.60
Purchase #4	$41.37	6.556%	$44.0822	$44.08	$44.10	$44.10
Purchase #5	$231.29	8.354%	$250.612	$250.61	$250.60	$250.60
Purchase #6	$210.25	3.237%	$217.0558	$217.06	$217.05	$217.10
Purchase #7	$133.28	5.351%	$140.4118	$140.41	$140.40	$140.40
7 purchase totals =	$1,046.49		$1,105.6121	$1,105.60	$1,105.60	$1,105.60